## Number Conversion Practice Questionsâ€¦

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The original version of this page is located at http: The following has been changed slightly, primarily by deleting material beyond the scope of CS Observe the preceding series of numbers. These are the commonplace numbers which we use almost every day for counting. Indeed, they are so familiar that you will be tempted not to look at them closely or think about them seriously; but do look at them and observe how they proceed, how they change.

Think about the pattern they follow and how the series 21 binary number systems exercises beyond what is listed above. Note that while we usually start counting at one, here we start at zero. Because the pattern is more clear. We start at zero and "count to nine", producing the unique single-digit decimal series which is repeated in the "one's column" over and over again, indefinitely.

We can see that the pattern in the one's column will continue, but what of the next column to the left? In 21 binary number systems exercises familiar decimal system, this is called the "ten's column"; and the unique single-digit decimal series is repeated in this column, 21 binary number systems exercises it was in the one's column but with a slight difference, namely, each digit appears ten times before the next digit appears.

That gives us ten ones concatenated with the single-digit decimal series to produce the "teens", then ten two's concatenated with the decimal series for the "twenties", and so on. Think for a moment about the third column that would eventually appear if we were to continue, i.

Here again we would see the single-digit decimal series repeated over and over in the one's column, and in the ten's column we would see each numeral of the decimal series repeated ten times before the appearance of the next numeral. In the third column the series would again be repeated indefinitely, but each numeral would appear one hundred times before the next numeral appears.

So in the one's column a "1" appeared once as the decimal series was iterated; in the ten's column a "1" appeared ten times during one series' iteration, and in the "hundred's column" it would appear one hundred times. Will it then appear one thousand times in the "thousand's column", before we see a "2"? Of course, as we all know.

We say that the number of times a digit will be repeated in each "place to the left" is increased by a power of ten. 21 binary number systems exercises pattern, though familiar, is worth noting, for we will have reason to recall it momentarily.

The ten single-digit numerals, "0" through "9", make up the symbols of our numbering system. No matter how high we count, we still use 21 binary number systems exercises these ten numerals in an ordered, repetitive pattern.

These are Arabic numerals, the ten symbols which were adopted for numerals as the Arab culture became literate centuries ago. Other numeral systems have been used by various societies, but this one has become the modern, world-wide standard, universally adopted in literate countries today. An example of a different numeral system which is familiar to Western students is the system of Roman numerals, which uses selected Roman letters to double as numerals as well as alphabetic characters: Our numbering system uses ten different numerals and is known as a decimal system from decemthe Latin word for tencf also dekaGreek.

Why are there ten numbers in the series? Why not six 21 binary number systems exercises nine? The answer is in your hands. Had we no thumbs, for instance, we would undoubtedly have developed an octal base 8 numbering system instead 21 binary number systems exercises a decimal one for our ordinary counting purposes. What would such a system look like?

Assuming the same historical development and the same conventions in ordering the series, we can surmise that it would be 21 binary number systems exercises to the decimal one:.

This is, in fact, an octal system of numbering which is used today in computer science. Note its similarity to the familiar decimal system. The unique single-digit series is again repeated indefinitely in the one's column; only this time the series has eight numbers instead of ten.

The decimal system is sometimes called base tenand the octal system, base eight. So where is the eight in the series above, someone might ask. It's just where you would expect it, right after the seven, just as the ten is right after the nine in the first series. But that looks like a ten, you object.

In base ten a "10" is a ten, in base eight a "10" is an eight. What about base five? Right, "10" is five; and so on for numbering systems with other bases. What about base twelve, you ask? Even there, a "10" is a twelve. With bases 21 binary number systems exercises than ten, alphabetic characters are used to "fill in the gaps", i. A is ten and B is eleven. Now let's take a look at base two, what is known as the binary system.

Just as there are ten numerals in the deci mal system, so are there two numerals in the bi nary system: Using the principles we have been developing, take a pencil and paper and write down what you think would be the first three numbers in the binary series of numbers, i.

You should have the following series:. Just as a "10" is a ten in base ten and a five in base five, in base two 21 binary number systems exercises "10" is a two. And two follows one, just as expected. We had ten numbers in the unique single-digit series in base ten, and eight numbers in the 21 binary number systems exercises single-digit series in base eight. Likewise, we have two numbers in the unique single-digit series in base two. If the similarities continue, we can expect this series to be repeated indefinitely in the one's column.

Indeed, with the addition of "three" the series becomes. We see that the pattern in the one's column continues: What about the second "column" or "place", just to the left of the one's column? Here we see two and three represented by what look like ten and eleven to our "decimal eyes". Since these correspond in a way to the decimal teens, can we expect the next parts of this series to be the "twenties"?

If so, we could expect "20" and "21" to be the next numbers in this series; but there is no numeral "2" in base two. We have just seen that two is represented in base two by "10". Do we then replace the "2" in "20" and "21" by "10" to get "" and ""?

Can you guess the next number in the series? One way to think about it is to continue the analogy in which we said that "10" and "11" correspond 21 binary number systems exercises the decimal teens and "" and "" correspond to the decimal twenties. We could then expect the "thirties" to follow, 21 binary number systems exercises we would need a three concatenated with a zero.

Since a three in binary is "11", we would have "" as the next number in our series, which is correct. Another way to think about it is to notice that the numerals "0" and "1" alternate in the one's column but that they then come in pairs in the next column. The pattern is clearer if we show 21 binary number systems exercises first eight numbers in the series and include leading zeros. Recall the pattern that we discovered earlier in decimal numbers in which each column to the left goes up by a factor of ten.

Even the short series above shows the "0's" and "1's" alternating in the one's column but coming in pairs in the "two's column". In the "four's 21 binary number systems exercises they even seem to be in 21 binary number systems exercises of four, which is, indeed, the 21 binary number systems exercises. And in the eight's column they come in groups of eight.

This is one of those interesting and handy quirks often found in numbers which has made mathematics so fascinating to many. It should prove helpful to you while learning the binary number system. Take the binary number, Does it represent the quantity ten thousand eleven?

No, of course not. We have already learned enough to know not to look on binary numbers with our "decimal vision". This number would represent that quantity only in the decimal system, not in the binary system, where it represents nineteen. But how are we to figure out that it is nineteen?

We use a procedure analogous to that which we use in base ten; but in base ten it is automatic, in base two we have to do it deliberately. Recall that each column "goes up" by a factor of two, and then move through the number from right to left in the following fashion: Simple conversions of a decimal number to binary representation require knowledge of the first eight powers of two, viz, 1, 2, 4, 8, 16, 32, 64, Let us convert the decimal number twenty-five 25 to binary.

We have to ask first what is the largest power of two that will go into our number. Scanning the list of the first eight powers, we see that sixteen is the largest that will go into twenty-five. This means that the number twenty-five has one sixteen in it, so we will want a "1" in the 16's 21 binary number systems exercises of our binary number.

It also means that the 16's column will be the left-most column in our binary number. So at this point we have:. Next we subtract sixteen the highest power so far from our original number, giving a nine. We repeat the process: So twenty-five "has an eight in it", and we put a "1" in the 8's column:. Now we subtract the eight from the nine, leaving one; and since one is the highest power of two which will go into one, we put a "1" in the 1's column:.

The quantity twenty-five is thus broken down into three quantities: What of the 4's and the 2's columns? Surely you can now guess that they will contain "0's":. Do the following as an exercise to familiarize yourself with these methods of converting between binary and decimal representation. Arithmetic operations are possible on binary numbers just as they are on decimal numbers.